RAM in XP Pro ?

scbs29 wrote:

Hello all
I am considering upgrading my pc, Pentium 4 dual core 3GHz, 2GB
DDR ram to something a bit faster.If I do upgrade I have pretty
well decided on an AMD Phenom II X4 965 Black Edition and an
Asus MSA78L/USB3 mobo. Another requirement is to increase the
amount of RAM. My mobo at the moment, ASRock P4VM890 will only
accept up to 2GB DDR, and I would like to go to 4GB DDR3 since I
have started doing some video editing.
I have been looking at RAM in XP and have found various reports
that XP 32Bit will only handle 2Gb, 3Gb, 4Gb depending where you
look. Can anyone shed light on this? Would XP Pro 32Bit handle 4
GB RAM with the above processor and mobo. I do not want to
switch to Windows 7 because I prefer XP and some software that I
use will not run on Win7.

32-bit Windows can use up to 4GB of RAM, but only 3GB is available
for user applications. By default, the upper 2GB of address space
(0x80000000-0xFFFFFFFF) is reserved for system (kernel, drivers,
cache) and left the lower 2GB of address space (0x00000000-
0x7FFFFFFF) for user applications.

This can be "tuned" to make 3GB of address space (0x00000000-
0xBFFFFFFF) available for user applications with one condition: the
applications must support memory addresses between 0x80000000-
0xBFFFFFFF, since some programs may hardcode memory addresses above
0x7FFFFFFF as invalid. This tuning thus, decreases the address
space used for system to only 1GB.

I haven't personally tested this, but VMWare v4 allocates memory
for VMs in system memory space (you can see it via Task Manager),
so you'll have less memory for them.

More details:

"Memory Limits for Windows Releases"
http://msdn.microsoft.com/en-us/lib...p/aa366778
(v=vs.85).aspx

"4-Gigabyte Tuning"
http://msdn.microsoft.com/en-us/lib...p/bb613473
(v=vs.85).aspx